\documentclass{standalone}
\usepackage{graphicx}
\setlength{\fboxrule}{1pt}
\setlength{\fboxsep}{3pt}
\begin{document}
\resizebox{7cm}{!}{\fbox{\mbox{Left}\quad\phantom{Right}}}
%test:
%\makebox[0pt][l]{\includegraphics{left.eps}}\includegraphics{right.eps}
\end{document}